Polycarbonates are used in many commercial and industrial applications because of their strength and other properties. Of particular importance are BPA-polycarbonates formed in whole or in part from bisphenol A (BPA) monomers.
BPA is commonly formed from the reaction of phenol and acetone. For example, U.S. Pat. Nos. 4,156,098, 4,375,567, 5,087,767, 5,248,839, 6,784,324, and 6,939,994 disclose processes for making BPA from phenol and acetone. In the adduct-crystallization method, acetone is reacted with excess phenol over an acidic IER (Ion Exchange Resin) catalyst bed. The product solution is cooled and BPA crystallizes out as a phenol adduct. The solid BPA adduct is removed by filtration. Most of the filtrate is recycled to the reactor although a portion is purged from the system. The BPA adduct is then melted and stripped of phenol in a desorber. Recovered phenol is recycled to the reactor and the clean BPA is then sent forward to polymerization.
Phenol can be made from the partial oxidation of benzene or benzoic acid, by the cumene process, by the catalytic dehydrogenation of cyclohexanone or cyclohexanol or by the Raschig process. It can also be found as a product of coal oxidation. Phenol used in the production of BPA today is typically greater than 99.9% purity and is derived from fossil fuel sources (petroleum or coal). The rising costs of such products, and their non-renewable nature makes these routes to the preparation of phenol less desirable. Thus, there is interest in preparation of phenols from renewable sources. For example, U.S. Pat. Nos. 4,420,644 and 4,647,704 describe catalyzed hydrocracking of lignin to produce phenol and other products. U.S. Pat. No. 4,900,873 discloses preparation of phenolic compounds by thermal decomposition of a lignin-containing material. Addition of double ring aromatic hydrocarbons such as naphthalene or biphenyl is taught to increase the yield of phenolic products. U.S. Pat. No. 4,605,790 describes a process for the preparation of phenol from mixed phenols obtained from coal or biomass. Frost et al, Angew. Chem. Int. Ed., 2001, 40(10) p 1945-1948 describes a shikimic acid bio-route to phenol. The preparation of phenol from glucose has also been described. (Applied and Environmental Microbiology, 2005, 71(12), p 8221-8227.
Acetone for bulk synthetic applications is also similarly derived from fossil sources. Acetone is commonly made by the Hock process wherein cumene is hydroperoxidated and then cleaved to form phenol and acetone. In some cases, the phenol and acetone can be directly reacted without intermediate purification to produce a BPA end product. Acetone is also made commercially from oxidation of isopropanol, which in turn can be produced from hydration of propylene. (see, for example, U.S. Pat. No. 4,352,945).
Acetone can also be derived from renewable sources, for example by reaction from bio-derived ethanol, or by fermentation processes. Bioacetone made by fermentation shows similar impurities as found in cumene-derived acetone by GC determination ((mesityl oxide and diacetone alcohol) both at <100 ppm levels). Bioacetone has also been made from pyrolysis of calcium acetate at 430-490° C. (Industrial and Engineering Chemistry, 1924, p 1133-1139) or more reasonably from Hock oxidative cleavage of terpene-derived p-cymene (‘Catalytic aspects in the transformation of pinenes to p-cymene’, APPLIED CATALYSIS A: GENERAL 215 (2001) p 111-124), but neither of these routes to acetone appears to be commercially practiced or feasible to acetone.
It would be desirable to be able to make BPA, and then polycarbonates from bio-derived phenol and/or acetone, or from bio-derived cumene in order to make materials incorporating BPA, including polycarbonates less dependent on fossil fuels.